Fe43.4Pt52.3Cu4.3 polyhedron nanoparticle with heterogeneous phase structure, preparing method and application thereof

Abstract

A Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 heterogeneous phase structure polyhedron nanoparticle, a preparing method and an application as an efficient fuel cell oxygen reduction catalyst are provided. The Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 heterogeneous phase structure polyhedron nanoparticle, includes: three elements of Fe, Pt and Cu; wherein the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 heterogeneous phase structure polyhedron nanoparticle has a heterogeneous phase structure in which face-centered cubic and face-centered tetragonal coexist; wherein the heterogeneous phase structure is a face-centered tetragonal phase shell and face-centered cubic core with a high crystal plane index; a surface of the polyhedron nanoparticle has 1 to 2 atomic layers of enriched with Pt; a diameter distribution of the nanoparticles is at a range of 4.5 to 14.5 nm, and an average size is 8.4 nm. In the invention, hexadecylamine, iron acetylacetonate, copper acetylacetonate, platinum acetylacetonate, and 1,2-hexadecanediol are uniformly mixed, and oleylamine and oleic acid are added, condensed refluxed at 320-330 C.

Claims

1. A Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 heterogeneous phase structure polyhedron nanoparticle, comprising: three elements of Fe, Pt and Cu; wherein the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 heterogeneous phase structure polyhedron nanoparticle has a heterogeneous phase structure in which face-centered cubic and face-centered tetragonal coexist; wherein the heterogeneous phase structure is a face-centered tetragonal phase shell and face-centered cubic core with a high crystal plane index; a surface of the polyhedron nanoparticle has 1 to 2 atomic layers enriched with Pt; a diameter distribution of the nanoparticles is at a range of 4.5 to 14.5 nm, and an average size is 8.4 nm.

2. A method for preparing the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 heterogeneous phase structure polyhedron nanoparticle as recited in claim 1, comprising steps of: (1) taking an appropriate amount of liquid cetylamine solvent and placing in a four-necked glass flask, then passing high purity nitrogen into the four-necked glass flask for 20-40 minutes, and then sequentially adding iron acetylacetonate, copper acetylacetonate, platinum acetylacetonate and 1,2-hexadecanediol to the four-necked glass flask, and finally stirring at 80 to 120 C. until raw materials are completely dissolved, wherein an entire stirring process is performed under a nitrogen flow to obtain a reaction precursor solution; (2) adding oleylamine and oleic acid to the reaction precursor solution obtained in step (1) according to a ratio, and continually stirring at 80-120 C. until completely and uniformly mixed, and continuing to pass nitrogen into a reaction system; (3) slowly heating the solution obtained by uniformly mixing in step (2) to a temperature at a range of 320-330 C., condensing and refluxing for 3 hours, and controlling an entire reaction process to be performed under stirring and nitrogen flow; (4) after the reaction is completed, terminating heating, and naturally cooling a temperature of the reaction system to 80 C., taking out a product obtained, centrifuging, washing for 2 to 4 times to obtain a washed black residual product, which is the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 heterogeneous phase structure polyhedron nanoparticle.

3. The method for preparing the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 heterogeneous phase structure polyhedron nanoparticle as recited in claim 2, wherein the liquid cetylamine solvent in the step (1) is prepared by melting solid cetylamine, wherein a melting temperature is at a range of 60 to 100 C.

4. The method for preparing the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 heterogeneous phase structure polyhedron nanoparticle as recited in claim 2, wherein a molar ratio of the iron acetylacetonate, the copper acetylacetonate, and the platinum acetylacetonate in the step (1) is 1:1:2.

5. The method for preparing the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 heterogeneous phase structure polyhedron nanoparticle as recited in claim 2, wherein an amount ratio of the cetylamine to the platinum acetylacetonate in step (1) is 50 ml: 1 mmol

6. The method for preparing the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 heterogeneous phase structure polyhedron nanoparticle as recited in claim 2, wherein in step (1), a molar ratio of the platinum acetylacetonate to the 1,2-hexadecanediol in the step (1) is 4:15.

7. The method for preparing the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 heterogeneous phase structure polyhedron nanoparticle as recited in claim 2, wherein in step (2), a molar ratio of the oleylamine to the platinum acetylacetonate is 20:1; a molar ratio of the oleylamine to the oleic acid is 1:1.

8. (canceled)

9. An oxygen reduction catalyst comprising the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 heterogeneous phase structure polyhedron nanoparticle as recited in claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIGS. 1(a) and (b) are respectively low-magnification STEM images and particle size statistics diagrams of the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 polyhedral nanoparticles prepared in Embodiment 1 of the present invention.

[0027] FIG. 2 is a high-resolution STEM image of Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 polyhedral nanoparticles prepared in Embodiment 1 of the present invention.

[0028] FIG. 3 is an analysis diagram of an exposed crystal plane of a single Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 polyhedron nanoparticle prepared in Embodiment 1 of the present invention.

[0029] FIG. 4(a) and FIG. 4(b) are cyclic voltammograms of Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 polyhedral nanoparticles and a commercial Pt/C catalyst prepared in Embodiment 1 of the present invention.

[0030] FIG. 5 is a comparison diagram of an ORR polarization curve of a Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 polyhedral nanoparticle and a commercial Pt/C catalyst prepared in Embodiment 1 of the present invention.

[0031] FIG. 6 is a graph comparing the mass activity of Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 polyhedral nanoparticles and a commercial Pt/C catalyst prepared in Embodiment 1 of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific implementation examples. This embodiment is implemented on the premise of the technology of the present invention, and detailed implementations and specific operating procedures are now given to illustrate the invention is inventive, but the scope of protection of the present invention is not limited to the following implementation cases.

[0033] Based on the information contained in this application, various changes in the precise description of the invention can be easily made by those skilled in the art without departing from the spirit and scope of the appended claims. It should be understood that the scope of the invention is not limited to the defined processes, properties, or components, as these embodiments and other descriptions are merely for illustrative purposes to illustrate specific aspects of the invention. In fact, it will be apparent to those skilled in the art or related fields that various changes that can be made to the embodiments of the present invention are within the scope of the appended claims.

[0034] In order to better understand the present invention without limiting the scope of the present invention, all numbers used in the present application indicating amounts, percentages, and other numerical values are to be understood in all cases as modified by the word about. Therefore, unless stated otherwise, the numerical parameters set forth in the description and appended claims are approximations that may vary depending on the ideal properties sought to be obtained. Individual numerical parameters should be considered, at a minimum, based on the significant figures reported and through conventional rounding methods.

Embodiment 1

[0035] In this embodiment, a method for preparing the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 polyhedron nanoparticle with heterogeneous phase structure comprising steps of:

[0036] (1) melting cetylamine in a solid state into a liquid state at 80 C.;

[0037] (2) taking 20 ml of cetylamine solvent melted in the liquid state in step (1) and placing in a four-necked glass flask, then passing high-purity nitrogen into the four-necked glass flask for 30 min, and then adding 0.2 mmol of iron acetylacetonate, 0.2 mmol of copper acetylacetonate, 0.4 mmol of platinum acetylacetonate, and 1.5 mmol of hexadecanediol in sequence to the cetylamine solvent, and finally stirring at 80 C. for 10 min to completely dissolve solid raw materials, wherein a whole stirring process is performed under a condition of nitrogen flow to obtain a reaction precursor solution;

[0038] (3) adding 8 mmol of oleylamine and 8 mmol of oleic acid to the reaction precursor solution obtained in step (2), and continuing stirring at 80 C. until the solution is completely and uniformly mixed, and continuing to pass nitrogen into a reaction system;

[0039] (4) heating the solution completely and uniformly mixed in step (3) to a temperature of 320 C., performing reflux condensation for 3 hours, wherein a whole reaction process is controlled to be carried out under agitation and nitrogen flow;

[0040] (5) after the reaction is completed, terminating heating and allowing the reaction solution to cool naturally at a room temperature, when the temperature drops to 80 C., adding 50 ml of a mixed solvent composed of anhydrous ethanol and n-hexane in a volume ratio of 1:1 to an obtained product, then dividing into aliquots and transferring into a centrifuge tube, centrifuging at 5000 r/min, removing a supernatant with yellow-brown color obtained by centrifugation, and then adding an identical mixed solvent with the same proportion to the centrifuge tube, centrifuging, and repeating the operation three times in the same way until the supernatant is colorless and transparent, and in such a manner that a washed black residual product is obtained, that is, the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 polyhedron nanoparticle with the heterogeneous phase structure according to the present invention.

[0041] The following specifically analyzes the test results of the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 polyhedron nanoparticle with heterogeneous phase structure prepared in the Embodiment 1:

[0042] FIG. 1 is a low-resolution STEM image and a statistical analysis diagram of a particle size of Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 nanoparticles synthesized in the Embodiment 1. It can be seen from FIG. 1 that the nanoparticles synthesized in this embodiment have a uniform size, a diameter at a range of 4.5 to 14.5 nm, and an average size of 8.4 nm.

[0043] FIG. 2 is a high-resolution STEM image and crystal structure analysis of the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 nanoparticles synthesized in the Embodiment 1. It can be seen from FIG. 2 that the obtained particle body phase mainly has a face-centered cubic structure, the particles have apparent surface crystal planes exposed, and some of the particle surfaces have characteristic crystal planes (001) and (110) with the face-centered tetragonal structure. It is shown that the synthesized Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 nanoparticles are partially heterogeneous phase polyhedral particles in which fcc and fct coexist.

[0044] FIG. 3 is a high-resolution STEM image and a surface exposed crystal plane analysis image of a single Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 nanoparticle of the product synthesized in the Embodiment 1. The results show that the exposed crystal planes are the (001), (110) and (111) crystal planes with the face-centered tetragonal phase.

Embodiment 2

[0045] In this embodiment, a method for preparing the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 polyhedron nanoparticle with heterogeneous phase structure comprising steps of:

[0046] (1) melting cetylamine in a solid state into a liquid state at 60 C.;

[0047] (2) taking 100 ml of cetylamine solvent melted in the liquid state in step (1) and placing in a four-necked glass flask, then passing high-purity nitrogen into the four-necked glass flask for 30 min, and then adding 1 mmol of iron acetylacetonate, 1 mmol of copper acetylacetonate, 2 mmol of platinum acetylacetonate, and 7.5 mmol of hexadecanediol in sequence to the cetylamine solvent, and finally stirring at 100 C. for 10 min to completely dissolve solid raw materials, wherein a whole stirring process is performed under a condition of nitrogen flow to obtain a reaction precursor solution;

[0048] (3) adding 40 mmol of oleylamine and 40 mmol of oleic acid to the reaction precursor solution obtained in step (2), and continuing stirring at 100 C. until the solution is completely and uniformly mixed, and continuing to pass nitrogen into a reaction system;

[0049] (4) heating the solution completely and uniformly mixed in step (3) to a temperature of 325 C., performing reflux condensation for 3 hours, wherein a whole reaction process is controlled to be carried out under agitation and nitrogen flow;

[0050] (5) after the reaction is completed, terminating heating and allowing the reaction solution to cool naturally at a room temperature, when the temperature drops to 80 C., adding 250 ml of a mixed solvent composed of anhydrous ethanol and n-hexane in a volume ratio of 1:1 to an obtained product, then dividing into aliquots and transferring into a centrifuge tube, centrifuging at 4000 r/min, removing a supernatant with yellow-brown color obtained by centrifugation, and then adding an identical mixed solvent with the same proportion to the centrifuge tube, centrifuging, and repeating the operation three times in the same way until the supernatant is colorless and transparent, and in such a manner that a washed black residual product is obtained, that is, the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 polyhedron nanoparticle with the heterogeneous phase structure according to the present invention.

Embodiment 3

[0051] In this embodiment, a method for preparing the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 polyhedron nanoparticle with heterogeneous phase structure comprising steps of:

[0052] (1) melting cetylamine in a solid state into a liquid state at 100 C.;

[0053] (2) taking 40 ml of cetylamine solvent melted in the liquid state in step (1) and placing in a four-necked glass flask, then passing high-purity nitrogen into the four-necked glass flask for 30 min, and then adding 0.4 mmol of iron acetylacetonate, 0.40 mmol of copper acetylacetonate, 0.8 mmol of platinum acetylacetonate, and 3 mmol of hexadecanediol in sequence to the cetylamine solvent, and finally stirring at 120 C. for 10 min to completely dissolve solid raw materials, wherein a whole stirring process is performed under a condition of nitrogen flow to obtain a reaction precursor solution;

[0054] (3) adding 16 mmol of oleylamine and 16 mmol of oleic acid to the reaction precursor solution obtained in step (2), and continuing stirring at 120 C. until the solution is completely and uniformly mixed, and continuing to pass nitrogen into a reaction system;

[0055] (4) heating the solution completely and uniformly mixed in step (3) to a temperature of 330 C., performing reflux condensation for 3 hours, wherein a whole reaction process is controlled to be carried out under agitation and nitrogen flow;

[0056] (5) after the reaction is completed, terminating heating and allowing the reaction solution to cool naturally at a room temperature, when the temperature drops to 80 C., adding 100 ml of a mixed solvent composed of anhydrous ethanol and n-hexane in a volume ratio of 1:1 to an obtained product, then dividing into aliquots and transferring into a centrifuge tube, centrifuging at 5000 r/min, removing a supernatant with yellow-brown color obtained by centrifugation, and then adding an identical mixed solvent with the same proportion to the centrifuge tube, centrifuging, and repeating the operation four times in the same way until the supernatant is colorless and transparent, and in such a manner that a washed black residual product is obtained, that is, the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 polyhedron nanoparticle with the heterogeneous phase structure according to the present invention.

[0057] Identical test method as in Embodiment 1 was used to test the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 heterogeneous phase structure polyhedron nanoparticles prepared in the above Embodiment 2 and Embodiment 3. The STEM, particle size statistical analysis, crystal structure analysis, and high-resolution STEM and surface-exposed crystal plane analysis results of individual Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 heterogeneous phase structure polyhedron nanoparticle is basically consistent with the test results of the product obtained in Embodiment 1.

Application Embodiment 1

[0058] The Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 heterogeneous phase structure polyhedron nanoparticles obtained in the above Embodiment 1 are used to prepare an ORR catalyst. The method comprises the following steps of:

[0059] (1) dispersing the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 heterogeneous phase structure polyhedron nanoparticles powder obtained in Embodiment 1 in 10 ml of hexane, and performing ultrasonic treatment for 10 minutes until the dispersion is uniform, so as to obtain a Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 dispersion;

[0060] (2) taking 1 ml of the dispersion obtained in step (1), vacuum drying to obtain a powder, and testing XRF to obtain granular components;

[0061] (3) taking 0.1 to 0.5 ml of the dispersion obtained in step (1) and diluting to 2 ml with hexane.

[0062] (4) adding 1 to 3 mg of Cabot carbon black to the diluted solution obtained in step (3), dispersing ultrasonically for 1 h, and supporting the nanoparticles on the Cabot carbon black;

[0063] (5) after centrifuging at 5000 r/min and removing a supernatant, adding opropanol and diluted Nafion mixed solution with a volume ratio of 20:1 to the system to 1 ml, and performing ultrasonic treatment for 10 minutes to uniformly mix to obtain ORR catalyst dripping solution.

[0064] The obtained catalyst is tested for electrochemical performance. The electrochemical test method is as follows:

[0065] The equipment adopts Chenhua CHI 760 electrochemical workstation and PINE rotating disk electrode. The electrochemical test adopts a three-electrode test system. The Ag/AgCl electrode is the reference electrode, platinum is a counter electrode, and the catalyst material is coated on a glass-carbon electrode with a diameter of 5 mm as a working electrode. The electrolyte adopts 0.5 mM H.sub.2SO.sub.4. A cyclic voltammetry scanning speed is 50 m V/s, a polarization curve scanning speed is 5 mV/s, and a rotating electrode speed is 1600 r/min.

[0066] FIG. 4 is a cyclic voltammetry curve comparison of Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3nanoparticle and commercial Pt/C in argon-saturated 0.5 mM H.sub.2SO.sub.4 electrolyte, with a scanning speed of 50 mV/s. FIG. 5 is a comparison chart of the linear scanning voltammetry curve of Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 nanoparticles and commercial Pt/C in oxygen-saturated 0.5 mM H.sub.2SO.sub.4 electrolyte. The scanning speed is 5 mV/s and the rotating disk electrode speed is 1600 r/min. As can be seen from the test results in FIGS. 4 and 5, Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 polyhedral nanoparticles have excellent ORR performance with a half-wave potential of 0.80V, which is better than the half-wave of commercial Pt/C catalysts under the same test conditions with a potential of 0.75V, wherein the polarization voltage is reduced by 50 mV. Under half-wave potential conditions, the mass activity of Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 polyhedral nanoparticles is 10.9 times that of commercial Pt/C.

[0067] FIG. 6 shows the calculated results of the mass activity of the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 nanoparticles and commercial Pt/C at different electrode potentials. It can be seen from FIG. 6 that the Fe.sub.43.4Pt.sub.52.3Cu.sub.4.3 polyhedral nanoparticles synthesized by the present invention have more excellent mass activity than Pt/C.